Morse taper #3 to #4 adapter

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nnam

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I saw some going from #4 to smaller size #3. I have #3 and I want to be able to use #4 drill bits since I happen to have a bunch of them.
I know some people may say that may "overload" the lathe. However, I think as long as I don't force it or step drilling things, it should not cause an issue.

I post here for more responses for pros or cons to this from the experienced machinists.

Furthermore, and more importantly, I can't even find such a thing.

Some of my concern is that if I can find an adapter, it'll be sticking out a bit, shortening the length of work area, but that's not so much of my concern, at least currently.

Another option is is to sell the bits, and buy new bits that works. It just means I probably lose a lot of money on shipping and the hassle of selling them. I don't know if there is a good solution to this.
 
ok, I just suddenly found one solution that works. I am still open for more, since experienced machinists probably know better:

CXA tool post holder for MT4.
 
What sort of a machine do you have? I'm guessing that with a #3 in the TS, it about 12" - 16" machine.
I am a big fan of drilling from the tool post (so the CXA to #4 is a good choice. I did not know the CXA was available with a #4 - that is awsome.

You can get a #3 male to #4 female, with a torque arm. I have never used one (the drilling from the toolpost is just so slick, I can't really see an advantage to using the tailstock). Using the adapter, without the torque arm I think would be a bad idea (though on the little anti-rotation key, also you would not want the tool to slip in the taper - if you don't have the tang socket in the tailstock and not all lathes do have the tang slot).
 
The MT3 male to MT4 female adapters are certainly available, but they do require a lot of stick out. Here's a US-made one, but you can get a Chinesium one for about half the price:

https://www.mscdirect.com/product/details/03732070

Presence of a tang shouldn't be a major consideration. Properly installed tooling shouldn't put any force on the tang. Other than ejecting tooling, the tang is, more or less, a historical artifact. It can't generate enough force to make up for the taper slipping.

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Another options (factory available with DS&G, Mazak, probably others makes with heavy pattern offerings) is a dedicated plinth that bolts directly to the cross slide. How big are the drills? Strictly speaking, you won't overload the spindle, if you go easy, the cross slide should be fine too.

As I said above, I am a fan of using a CXA holder on the toolpost (I have a CXA on my 15" lathe, but only a CXA-#3MT holder). I have not fitted an anti-rotation arrangement, so it is possible for the post to slip (which has happened to me, but if you are paying attention (which you better be) then it is not a big deal.

My largest drill is 1-1/4" , which I have in both #3MT and #4 MT. I very rarely use such a large drill. Any hole of size - I'm going to bore it anyway.
 
my lathe is a Leblond regal 15".

Yes, boring the hole is a good option. I am not quite sure what you meant about "slip" Do you mean the CXA tool post just loosen up on the holder? The holder is at a vertical angle though, so maybe you meant the tool post just rotate on the compound slide?

It's my lucky day today though. I just found out that my 20" drill press uses MT4 for the chuck. I removed the chuck with a wedge and I was able to put the drill bit in with no problem. This is great bonus. Not everything I drill has to be on the lathe. Odd shapes, large shape, etc.

I don't drill larger size than 1" alot, but I think there were cases before that I needed it.
 
pstemari said:
The MT3 male to MT4 female adapters are certainly available, but they do require a lot of stick out. Here's a US-made one, but you can get a Chinesium one for about half the price:

https://www.mscdirect.com/product/details/03732070

Presence of a tang shouldn't be a major consideration. Properly installed tooling shouldn't put any force on the tang. Other than ejecting tooling, the tang is, more or less, a historical artifact. It can't generate enough force to make up for the taper slipping.

Sent from my Pixel XL using Tapatalk
Click to expand...

Wow, nice. I searched alot, couldn't find it, but you have it so quick. As I found out more above, looks like I may opt for the CXA option if I need it, but this is a very good choice. Now that I can use the drill press, and just use bore for large hole in the lathe, my needs for this adapter is much less.
 
nnam said:
my lathe is a Leblond regal 15".

Yes, boring the hole is a good option. I am not quite sure what you meant about "slip" Do you mean the CXA tool post just loosen up on the holder? The holder is at a vertical angle though, so maybe you meant the tool post just rotate on the compound slide?

I don't drill larger size than 1" alot, but I think there were cases before that I needed it.
Click to expand...

By "slip" I mean that the post rotates slightly on the compound. I have made ~2" diameter washer 0.05" with a good portion of the center relieved, so that the center post bolt loading is further out. I don't recall if I have had it slip since I added the washer.

Once the middle has been opened up enough for a good sized boring bar (i.e. 1") - it does not take long to clear some space.

It sounds like you must have landed a great bargain deal on some large drill bits. Now you are figuring out how you can set them up to use them? That you would rarely use them and have other good options for opening up the center of a piece of bar - that is totally beside the point.

Drilling is generally a roughing operation, so depending on the project - you might be able to open up the first hole on that 20" drill press and then transfer the job to the lathe? i.e. perhaps you don't needs to spend much time sorting out a solution that you almost never would actually need to use?

Very cool to have a "bunch" of big drill bits. I scammed a 1-7/8 (thrashed MT5 taper) - for free. Again, I totally don't need it, but it is cool!

Please post a picture of your collection.
 
I always wanted larger drill bits due to some prior need for them. Having a set of used bits for good price is very nice and if I can use it in one or two times, it would be worth it. I think they're made in the US, so I think they have good quality, although they look very well used. I looked closely and most of them can be good bits, especially if I can sharpen some of them. The cutting sides are very good. The tips are mostly good. But the sides are what I concern because I can only sharpen the tips.

Here is a picture of them. I got them part of something else, so I don't know their exact cost for me, but I think overall, I got decently good price for a well used set.

drill-bits-png.275276


drill bits.png
 
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